Originally published as e-novellas, they are now together in one print volume.
"Our print volumes have been holding steady or growing some."
More than 100,000 new print volumes are acquired each year.
It was first published as a series of print volumes from 1990 to 2000, and then on a website from 2002.
The new series began with a digital volume and has since extended to three print volumes.
In the print volume, both pages and font are bigger.
Further print volumes had been planned but the publisher ceased operations in early 2010.
Mid-volume typically describes print volumes of between 100,000 and one million pages per month.
Furthermore, the energy cost is reduced due to the fact that they share the same heated print volume.
The library houses over 3.9 million print volumes, including nearly 46,000 serial titles.